1// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include "ipc/ipc_channel.h"
6
7#include <limits>
8
9#include "base/atomic_sequence_num.h"
10#include "base/rand_util.h"
11#include "base/strings/stringprintf.h"
12
13#if !defined(OS_NACL)
14namespace {
15
16// Global atomic used to guarantee channel IDs are unique.
17base::StaticAtomicSequenceNumber g_last_id;
18
19}  // namespace
20#endif
21
22namespace IPC {
23
24// static
25std::string Channel::GenerateUniqueRandomChannelID() {
26  // Note: the string must start with the current process id, this is how
27  // some child processes determine the pid of the parent.
28  //
29  // This is composed of a unique incremental identifier, the process ID of
30  // the creator, an identifier for the child instance, and a strong random
31  // component. The strong random component prevents other processes from
32  // hijacking or squatting on predictable channel names.
33
34  int process_id = base::GetCurrentProcId();
35  return base::StringPrintf("%d.%u.%d",
36      process_id,
37      g_last_id.GetNext(),
38      base::RandInt(0, std::numeric_limits<int32>::max()));
39}
40
41}  // namespace IPC
42
43